BEIRUT, Jan 23 (Reuters) - Syrian armed rebel groups said on
Saturday they held the Syrian government and Russia responsible
for any failure of peace talks to end the country's civil war,
even before negotiations due to start in Geneva next week.

U.S. Secretary of State John Kerry said he was confident the
talks set for Jan. 25 would go ahead next week.

But negotiations look increasingly likely to stall with a
dispute over the composition of the opposition negotiating team,
and opposition demands that Russia halt bombing of civilian
areas and the Syrian government lift sieges as goodwill measures
before they will come to the table.

"We hold the Assad regime and its Russian ally responsible
for any failure of the political process due to their continued
war crimes," a joint statement from dozens of rebel factions
said.

It criticised Russian "meddling in the affairs of the
opposition delegation", a reference to Moscow demanding that the
opposition's negotiating team be expanded to include other
figures that could be deemed closer to its own thinking,
including the Kurdish PYD party.

Russia backs its longtime ally President Bashar al-Assad and
has bolstered pro-government forces with air strikes against
insurgent groups since September.

The rebels' statement was signed off by groups including the
powerful Jaysh al-Islam, whose politburo member Mohamad Alloush
is the chief negotiator on the High Negotiations Committee -- a
body drawn up by civilian and armed opposition groups after a
meeting in Riyadh last month.